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[media] v4l2-framework: replace g_chip_ident by g_std in the examples

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The framework documentation used the g_chip_ident op as an example. This
op has been removed, so replace its use in the examples by the g_std op.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Cc: Mauro Carvalho Chehab <mchehab@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Hans Verkuil 2013-05-29 07:59:57 -03:00 • committed by Mauro Carvalho Chehab
parent abbec2d401
commit 2249aa5c97
2 changed files with 12 additions and 14 deletions
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13
Documentation/zh_CN/video4linux/v4l2-framework.txt
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@ -247,7 +247,6 @@ i2c_client 结构体，i2c_set_clientdata() 函数可用于保存一个 v4l2_sub
这些结构体定义如下：
struct v4l2_subdev_core_ops {
int (*g_chip_ident)(struct v4l2_subdev *sd, struct v4l2_dbg_chip_ident *chip);
int (*log_status)(struct v4l2_subdev *sd);
int (*init)(struct v4l2_subdev *sd, u32 val);
...
@ -337,24 +336,24 @@ subdev->dev 域就指向了 v4l2_device。
注册之设备后，可通过以下方式直接调用其操作函数：
err = sd->ops->core->g_chip_ident(sd, &chip);
err = sd->ops->core->g_std(sd, &norm);
但使用如下宏会比较容易且合适：
err = v4l2_subdev_call(sd, core, g_chip_ident, &chip);
err = v4l2_subdev_call(sd, core, g_std, &norm);
这个宏将会做 NULL 指针检查，如果 subdev 为 NULL，则返回-ENODEV；如果
subdev->core 或 subdev->core->g_chip_ident 为 NULL，则返回 -ENOIOCTLCMD；
否则将返回 subdev->ops->core->g_chip_ident ops 调用的实际结果。
subdev->core 或 subdev->core->g_std 为 NULL，则返回 -ENOIOCTLCMD；
否则将返回 subdev->ops->core->g_std ops 调用的实际结果。
有时也可能同时调用所有或一系列子设备的某个操作函数：
v4l2_device_call_all(v4l2_dev, 0, core, g_chip_ident, &chip);
v4l2_device_call_all(v4l2_dev, 0, core, g_std, &norm);
任何不支持此操作的子设备都会被跳过，并忽略错误返回值。但如果你需要
检查出错码，则可使用如下函数：
err = v4l2_device_call_until_err(v4l2_dev, 0, core, g_chip_ident, &chip);
err = v4l2_device_call_until_err(v4l2_dev, 0, core, g_std, &norm);
除 -ENOIOCTLCMD 外的任何错误都会跳出循环并返回错误值。如果（除 -ENOIOCTLCMD
外）没有错误发生，则返回 0。